53 General and Physical Chemistry. Lamps for Spectra. 11. By ERNST BECKMANN (.%it. physikcd. Chenz., 1900, 35, 443--458).-The paper contains a large number of practical details of the apparatus previously described (Abstr., 1900, ii, 701). For the appreciation of these, reference must be made to the original, with its numerous illustrations. Action of Heat on the Absorption Spectra and Chemical Constitution of Saline Solutions. By W. NOEL HARTLEY (Sci. Trans. Roy. DubZ. Xoc., 1900, 7, [ii], 253--312).-The author has examined the absorption spectra of nickel, copper, chromium, cobalt, uranium, and didymium salts, as well as that of potassium per- manganate. The changes in the spectra accompanying dilution and rise of temperature were specially noted. The author's conclusions are summarieed as follows.When a definite crystalline hydrate dissolves in a solvent which is not water, and is without chemical action on it, the molecule of the salt remains unchanged in chemical composition. I n any series of salts which are anhydrous, and do not form well-defined crystalline hydrates, the action of heat up to 100" does not cause alteration in their absorptiol; spectra, beyond that which is usual with substances which undergo no chemical change by such rise of temperature. The change is usually an increase in the intensity of the absorption, or a slight widening of the absorption bands. As a rule, crystalline metallic salts in which water is an integral part of the molecule dissolve in water at the ordinary tempera- ture without dissociation of the molecule.Crystallised hydrated salts, dissolved in a minimum of water a t 20°, undergo dissociation by rise of temperature. The extent of the dissociation may proceed as far as complete dehydration of the compound, so that more or less of the anhydrous salt may be formed in the solution. The most stable com- pound which can exist in a saturated solution at 16" or 20" is not always of the same composition as the molecule of the crystallised solid a t the same temperature, since the solid may undergo partial dissociation from its water of crystallisation when the molecule enters into solu- tion. Saturated solutions of deliquescent salts combine with water, when diluted, to constitute molecules of more complex hydrated com- pounds in such solutions. When a saturated solution of a coloured salt undergoes a great change of colour on dilution, or any remarkable change in its absorption spectrum due to the same cause, the dilution i s always accompanied by a considerable development of heat.J. C. P. J. C. P. Dielectric Constants of Pure Liquids. By B. BERNARD TURNER (Zeit. physikal. Chem., 1900, 35, 385--430).-The author has made an exhaustive study of Nernst's method of determining dielectric con- stants (Abstr., 1894, ii, 437), and introduced several alterations. The various means of eliminating the external capacity are compared, and the use of that method recommended in which the capacity of the VOL. LXXX. ii. 554 ABSTRACTS OF CHEMICAL PAPERS, trough employed is measured (1) with rod and condenser plate, (2) with rod alone. The ebonite lid of the trough is found to be a source of weakness, and is replaced by a glass lid of suitable construction.For exact measurements, the temperature coefficient of the apparatus must be taken into account. The standard condensers are enlarged and improved, whilst alterations in the compensation resistances are also described. With these improvements, it is possible to determine capacities five or ten times more accurately than with the older form of apparatus. The dielectric constants of the following pure liquids have been very accurately determined : benzene, 2.288 ; o-nitrotoluene, 27.7 ; water, 81.1, all at 18’; these liquids may suitably be employed as standards. The dielectric constants of the following have been accurately deter- mined, but either the liquids are more variable, or their purity has not been so thoroughly tested : ether, 4.368 ; aniline, 7.31 ; m-xylene, 2.3’76 ; nitrobenzene, 36.45, all at 18’.The dielectric constants of 16 other liquids and a number of temperature coefficients have also been determined. J. C. P. Influence of Non-electrolytes on the Conductivity of Elec- trolytes. By ARTHUR HANTZSCH (Zeit. anorg. Chem., 1900, 25, 332-34O).--The addition of carbamide, thiocarbamide, ethyl or methyl alcohol, ether, acetone? pyridine, urethane, or mannitol to aqueous solutions of the chlorides of the alkali or alkaline-earth metals diminishes the conductivity slightly, and to approximately the same extent. The addition of urethane or carbamide to solutions of silver ni- trate produces a small diminution of conductivity, alcohol and mannitol have a rather larger effect, whilst thiocarbamide and pyridine have a very large effect.The addition of 2 mols. of pyridine to 1 of silver nitrate, for example, reduces the conductivity by more than 30 per cent. The conductivity of ammoniacal solutions of ammonium chloride or calcium chloride is rather less than the sum of the conductivities of the solutions separately. The difference is somewhat greater in the case of ammoniacal solutions of silver nitrate. The latter contain the complex ionAg(NH3)2, so that tohe mobility of this ion must be about the same as that of the simple ion Ag. The author considers that the results are best interpreted by Werner’s theory (Zeit. anorg. Chem., 1889, 3, 267).T. E. Decomposition-potentials of Fused and Solid Electrolytes. By CHARLES CORNFIELD GARRARD (Zeit. aaorg. Chem., 1900, 25, 273-312).-The salts are fused in hard glass tubes with clectrodes of pure carbon. The currents produced by the application of a series of E.M.F.’s are observed and plotted in a curve. Each change of direc- tion of this curve indicates the beginning of some decomposition. From the decomposition-potential (E) of a salt at the temperature T, and the temperature coefficient dE/dT, the heat of formation, Q, of the salt can be calculated by means of Helmholtz’s equation, &= E - TdE/dT. Where two decomposition points (E, and 3,) exist, two heats of formation may be calculated (Q1 and &,). These are corn- pared with the heat of formation determined by the calorimeter (&). The following table contains the principal numerical results :GENERAL AND PHYSICAL CHEMISTRY.55 Substance. Temp. I- NaI ............... KI ................ PbI, ............. PbCI, ........... CdCl, ............ CdBr, ............ CdI, ............... AgCl .............. AgBr ............ AgI (solid) ..... ZnC1, ............ ZnBr, .......... AgI .............. 650" 674 470 669 563 591 468 536 566 564 465 467 504 -I- 1-1- 55000 92200 0.812 0'833 0'435 0.80 0.715 0.62 0.515 0.760 0.469 0.348 0-5 44900 75000 28100 25300 18300 - 7.7 - 8.9 - 6.5 - 7.3 -6.5 0 -728 1.238 1'225 0 '91 0.681 1'505 1'21 - 6.2 - 8'0 Heat of formation. 46500 75700 29800 25000 20600 Q2. 1 Q. Lead Chloride and Iodide.-These salts are probabIg ionised as follows : PbI, = PbI* +I' and PbI.= Pb** + I'. The separation of the ions Pb** and I' from their charges will require one potential, that of the ions PbI* and z' another. Since P b I decomposes spontaneously into PbI,, and P b when it is separated from its electric charge, it is obvious that this change is not reversible, and requires a higher poten- tial than the reversible discharge of Pb** and I' ions. I n accordance with this, the values of Q1 agree well with those of Q for these salts. The first decomposition point is indistinct and not readily observed, whereas the second is well marked; it follows from this that the salts are mainly dissociated into PbI* or PbCl* ions. The results are quite similar to those obtained with water. A saturated aqueous solution of lead chloride deposits P b and Pb0, at 1.568 - 0.002 t volts (with platinum point electrodes).A saturated aqueous solution of lead bromide gives P b and Br at 1.306 volts (16'). The decomposition is the irreversible one through PbBr* ions. With fused lead bromide, the results were untrustworthy owing to an increase of resistance at the anode; the curious behaviour of aqueous solutions of oxalic acid is shown to be due to a similar cause. The saturated aqueous solution of cadmium chloride gives two de- composition points, showing that the electrolytic dissociation takes place in two stages. Cuprous chloride, when fused, conducts the current in accordance with Ohm's law, and shows no polarisation. Model to Show Ionic Migration. By W. LASH MILLER and FRAKK B.KENBXCK (Zed. physikal. Chem., 1900, 35, 440-442).--Two horizontal cords, carrying cardboard riders at fixed distances to repre- sent the ions and stretched by weights at one end, are made to move in opposite directions and with different velocities by means of pulleys t o which the other ends of the cords are attached; the diameters of the pulleys are in the ratio I : 2 : 3. This model shows how the ions are separated at the electrodes, and how the concentration of the inter- T. E. 5-256 ABSTRACTS OF CHEMICAL PAPERS, mediate solution is affected by the migration of the ions. The poten- tial difference between the electrodes may be represented by the driving pressure on the pulleys, so that the apparatus serves to illus- trate Ohm's law (compare Miiller, Abstr., 1900, ii, 643 ; Kohlrausch, Abstr., 1900, ii, 712).By VANDEVYVER- GRAU (Chern. Centr., 1900, ii, 923-924; from Ann. Chim. anal. appl., 5, 321--323).-See this vol., ii, 46. Thermochemistry of the Hyperacids of Zirconium, Cerium, and Thorium. By L. PISSARJEWSKY (J. Russ. Phys. Chem. Xoc., 1900, 32, 609-637. Compare Abstr., 1900, ii, 466).-The following heats of reaction have been determined : J. C. P. Determination of the Specific Heat of Fats. ZrO, (hydrated) + mH,SO, = Zr(SO,), + H,O, + H,O + (n - 2)H,SO, +9*671 Gal. ZrO, (hydrated) = ZrO, +O + 21.786 Cal. 2 0 , (hydrated) + mH2S04 = Ce,(SO,), + H,O, + 0, + 2H,O + 2Ce(S0,J2 + H,O, = Ce,(SO,), + H,SO, +O, + 33.576 Cal. CeO, (hydrated) +mH,SO, = Ce(SO,), + 2H,O + (n - 2)H,SO, + CeO, (hydrated) = CeO, (hydrated) + 0 + 20-392 CaI.Tho, (hydrated) = Tho, (hydrated) + 0 + 14.290 Gal. The heats of sclution of hydrated thorium peroxide (Th,O,) and oxide in dilute nitric acid are 34.368 and 29.893 Cal. repectively. By dissolving zirconium peroxide in excess of hydrogen peroxide solution in presence of an alkali hydroxide, the sodium (with 9H,O) and potassium (with 9H,O) salts of perzirconic acid, H,Zr,O,,, were prepared but could not be obtained in a pure state. By M. 5. WREWSKY (2 Russ. Phys. Chem. Xoc., 1900,32,593-609).--The vapour pressure of a solution of potassium carbonate in a mixture of methyl alcohol and water is found to increase with the proportion of salt present. If P is the vapour pressure of the aqueous alcohol and P, that of the aqueous alcoholic potassium carbonate solution, the value of (P, - P)/P diminishes as the temperature rises.Experi- ments made with salts of the alkali and alkaline-earth metals show that the change produced in the value of the vapour pressure of aqueous methyl alcohol when equivalent quantities of salts of the same acid are dissolved in it, increases as the molecular weight of the base of the salt increases, whilst salts of the same base with different acids produce effects which decrease as the avidity of the acid increases. Further, the changes produced in the vapour pressure of such solutions at any temperature by replacing potassium chloride by sodium chloride or potassium carbonate by sodium carbonate are identical; a similar relation holds for the replacement of potassium carbonate by potassium chloride and of sodium carbonate by sodium chloride.The system methyl alcohol-water-potassium carbonate separates into two layers (one containing excess of water and the other excess of (n - 3)H,SO, + 29.954 Cal. 0.897 Cal. T. H. P. Vapour Pressures of Aqueous Alcoholic Salt Solutions.GENERAL AND PHYSICAL CHEMISTRY. 57 alcohol) which are found to have equal vapour pressures, that of the water being lowered and that of the alcohol raised by the presence of the salt. T. H. P. Vapour Pressure of a Series of Benzene Compounds. By ADOLF WINRELMANN (Zeit. physikal. Chem., 1900, 35, 480-482).- A criticism of certain statements made by Woringer (see Abstr., 1900, ii, 709). J, C. P. Vapour Pressures of Binary and Ternary Mixtures. By FUNS A.H. SCHREINEMAKERY (Zeit. physikal. Chem., 1909, 35, 459-479).-The greater part of this paper, dealing with the system water-phenol, has already been abstracted (this vol., ii, 9). The author has further investigated the three-phase system : water-aniline. The vapour in contact with the two conjugate liquids. aniline-water and water-aniline, has at temperatures from 41-90° a composition inter- mediate between those of the liquids. At 5 6 ~ 3 ~ and 7 5 O , the vapour from aqueous solutions of aniline contains more aniline than the liquid. The experimental results for the system water-aniline are shown to agree with van der Waals’ formula (Zoc. cit.). The compo- sition of the vapour phase of the system water-phenol-aniline, the liquid and solid phases of which have been previously investigated (Abstr., 1899, ii, 739 ; 1900, ii, 135), has been determined at 5 6 * 3 O , in contact with two conjugate liquid phases.By HANS EULER (Bey., 1900, 33, 3202-3206. Compare Abstr., 1900, ii, 532).--The author holds that a catalytic agent affects the dissociation of the substances primarily concerned in a reaction, and applies this to the hydrolysis of ethyl acetate, When R’is the equilibrium constant of the reaction, and k and k’ the velocity constants of the two opposite component re- actions, then K=k/k’. The catalytic agent has no effect on the ratio I%/#, but alters the absolute value both of k and k’ in the proportion 1 : 1 + kH, where H is the concentration of the hydrogen ions yielded by the catalytic agent, Since the ratio k/k’ is unaltered by the cata- lytic agent, the free energy of the reaction (= RTlog,k/k’) is also un altered.J. C. P. Most General Form of the Laws of Chemical Kinetics for Homogeneous Systems. By RUDOLF WEGSCHEIDER (Jfonatsh., 1900, 21, 693-786. Compare Abstr., 1900, ii, 199).-A theoretical paper, much of which is not suitable for abstraction. The author de- duces general equations for the velocity of all kinds of reactions at constant volume in homogeneous systems. He discusses the form which the equation expressing the reaction must have, and the conditions which must be fulfilled in order (1) that the ratio of the velocities of two reactions which take place simultaneously is independent of the time ; (2) that the concentration of a substance which is produced and de- composed in parallel reactions remains unchanged ; (3) that the con- centration changes of two substances are in a ratio to one another which is independent of the time.The form of the equation for reac tion velocities with varying volume and (in the case of gases) with constant pressure is deduced, and the formulse obtained are applied to J. C. P. Theory of Chemical Catalytic Action.58 ABSTRACTS OF CHEMICAL PAPERS, Bodenstein’s experiments on the formation of water from hydrogen and oxygen (Abstr., 1899, ii, 733). J. C. P. Sensitiveness to Light of Hydrogen Peroxide in Aqueous Solution on Addition of Ferro- and Ferri-cyanide. By WLADIM IR A. KISTIAHOWBKY (Zeit. physikal. Chem., 1900, 35, 431--439).-When a few drops of potassium ferrocyanide are added to a 1 per cent.solution of hydrogen peroxide kept in the dark, the decomposition of the peroxide is very slow ; if, however, the liquid is placed in direct sunlight, a brisk effervescence is observed in a few minutes, especially on shaking. It is shown that the liberation of oxygen from hydrogen peroxide under these conditions is in accordance with the equation : k.t =loga/(a- x), where k is a constant, a the initial concentration, and x the quantity of the hydrogen peroxide de- composed. The value of k when the reaction takes place in sunlight is 10-20 times greater than the value obtained when i t takes place in the dark. It is not necessary that the liquid be illuminated the whole time; a minute’s illumination is sufficient to accelerate the de- composition to the extent mentioned.It is shown that this accelern- tion is not due to a rise of temperature, but probably to a catalytic agent formed in the light from ferrocyanide and ferricyanide, an agent which is permanent even when illumination is discontinued. J, C. P. Absorption of Water Vapour by Chemical Compounds. By W. I. BUSNIKOFF (J. Russ. Phys. Chem. SOC., 1900, 32, 551-593. Compare Abstr., 1899, ii, 360 and 409)-9.7340 grams of aqueous sulphuric acid of the composition H2S04 + 2*285H20, and 42.9056 grams of acid corresponding with the hydrate H2S04 + 0*338H20 were placed under the same desiccator and the concentrations of the two determined from time to time. A t the end of 787 days the respective compositions were H2S04+ 0.8’77K20 and H2S04 + 0.648H20 ; so that if interchange of water between two masses of aqueous sulphuric acid takes place in such a manner that one of them forms a hydrate containing less than 1H20, the other will also give a hydrate with less than 1H20. Next two masses of 043054 and 51.0118 grams respect- ively of the same acid of the composition H,SO4+@285H2O were placed under a bell jar in vessels of the same sectional area so that equal surfaces were exposed to the air ; it was found that the weights of water absorbed in the two cases were almost identical, the rate of absorption being independent of the composition of the acid between the limits H,SO, + 0*285H20 and H,SO, + 2.038H20.It was previously shown (Zoc. cit.) that the hydrate H2S04 + 4H20 possesses a greater power of absorbing water than the hydrates immediately weaker and stronger than it ; further experiments show that in this hydrate the affinity with which the water is held also has a maximum value.On exposing approximately equal quantities of phosphoric oxide and the hydrate H2S0, + 0*887H20 togetherunderadesiccator, it is found that the former absorbs more water than the latter. Other experi- ments with aqueous sulphuric acids show that hydrates containing between 12 and 12.5 or between 18 and 19 mols. of water per H2S04INORGANIC CHEMISTRY. 69 have greater powers of absorbing water than the adjacent lower and higher hydrates. The absorption of water vapour by sodium sulphate has also been studied, as well as the interchange of water between the hydrated salt and aqueous sulphuric acid, when placed under the same desiccator.In the latter case, 3.7280 grams of Na,SO,+ 11*654H20 and 1.1742 grams of H,SO, + 0*274H20 were employed, the composition of the hydrated sodium sulphate being, after successive periods of 24 hours : Na2S0,+ (1) 1 1-654H20 (initial value), (2) 7.80H20, (3) 5*704H20, (4) 4*345H28, &c. The affinities of these hydrates for water are (1) 0*047,(2), 0.074 and, (3) 0.110, and (4) 0.162 respectively, these numbers increasing in a geometrical progression with constant ratio about 1.50. I n the same way, the sulphuric acid absorbs water, forming a t the end of each 24 hours hydrates which have affinities for water increasing in geometrical progression with a constant ratio about 1.50. I n the case of anhydrous potassium carbonate, the affinities of the various hydrates for water increase geometrically with a ratio of about 1-40. Experiments mere also made on the removal of water from aqueous potassium carhonate by means of sulphuric acid placed in the same desiccator. Anhydrous sodium nitrate absorbs water vapour, yielding after successive intervals of 24 hours hydrates which have affinities f o r water nearly equal in value. When the water is removed from the hydrated nitrate by placing it together with sulphuric acid under a desiccator, the hydrates obtained at the end of each day's exposure have aanities for water of the values 0,077, 0.112, and 0.349 respect- ively, there being in this case no constant ratio. Similar experiments were made with potassium nitrate, the affinities of the various hydrates for water being 1 *74, 1 *48, 1-48, 1 *72 and 1.76 respectively. T. H. P.